This scatter plot ranks major US cities by population magnitude, with each circle’s position and radius encoding the city’s population in millions, while a blue color gradient adds an extra visual cue. The chart loads a CSV from a GitHub gist and uses `d3.csv` with `d3.autoType` to parse the data. It draws axes, gridlines, and labels using `d3.axisLeft`, `d3.axisBottom`, and SVG text elements, while `d3.scaleLinear`, `d3.scalePoint`, and `d3.scaleSqrt` map population to x-position, city name to y-position, and circle size, respectively. Interactive tooltips appear on hover via `d3.select` and mouse events.